Effect of head-up motion on stroke parameters and arm coordination of the front crawl in surf lifesavers

Aim: The aim of this study was to examine the effect of the head-up motion on the stroke parameters and arm coordination of the front crawl swim in lifesavers. Methods: Twelve lifesavers, who were skilled at head-up motion, swam front crawl and head up motion at surf racing speed (50 m in 35 s) in swimming-mill. Two video cameras were used to determine stroke rate, length, and phase as well as arm coordination for each arm. Arm coordination was quantified using the index of coordination (IdC_p and Id-C_Np). IdC_p was the lag time between the end of propulsion on the breathing side and the beginning of propulsion on the non-breathing side and was expressed as a percentage of the duration of a complete stroke. IdC_NP did the converse. Results: The head-up swim showed significantly higher stroke rates and shorter stroke length than those of the front crawl. In the head-up swim, the breathing side arm showed a significantly longer non-propulsive phase compared to that for the non-breathing side arm. For the breathing side arm, head-up swim showed a significantly longer stretch phase compared to that in front crawl. No significant differences of IdC were noted between the non-breathing and breathing arms in the swimming trial. Conclusion: These result indicated that when lifesavers do front crawl and head up swim, they changed some stroke phases, not IdC. In this regard, coaches must instruct lifesavers about the specific forms required, especially each phase for head-up motion.